This invention relates to a process for scavenging hydrogen sulfide and mercaptans from materials, particularly fluids, by contacting the materials containing the sulfur compounds with maleimides.
The reactivity of olefins with sulfur compounds is known in the art. Ger. Offen. No. 2,710,529 discloses the reaction of acrylamide with hydrogen sulfide in the presence of aqueous base to produce 3,3'-thio-di-propionamide. The reaction of sulfur compounds with .alpha.,.beta.-unsaturated anhydrides to produce the corresponding substituted mercaptan anhydrides is disclosed in B. C. Trevodi and B. M. Culbertson, Maleic Anhydride, 1982; and F. B. Zienty, B. D. Vineyard and A. A. Schleppnik, Journal of Organic Chemistry, 1962, p. 3140. However, these processes generally require the addition of an alkaline catalyst. The biological action of maleimide is known as disclosed in Biokhimiya, 1975, 40 (3), 489-496. Maleimide has been shown to be an effective -SH blocking reagent which can inhibit many enzymes whose active site utilizes an -SH group.
Hydrogen sulfide and mercaptans, particularly the lower carbon mercaptans, when present in a variety of commercial or industrial system materials are known to have undesirable effects, for example, they can be toxic, odoriforous and corrosive. Therefore, it is desirable to have a simple process for the removal of these noxious substances from these materials.
U.S. Pat. No. 4,374,732 discloses the removal of organo-sulfur impurities from organic or aqueous solutions by contacting said solutions with polymers containing functional groups consisting of metal salts of N-halosulfonamides. However it is desirable that the reactive polymer be insoluble in the fluid media to be purified in the practice of that process.
In the process of this invention, it has been found that hydrogen sulfide and mercaptans can be removed from materials, particularly fluids, containing them by simply contacting such fluids with the maleimides without requiring insolubility of the maleimide in the fluid media to be purified. Maleimides are not only useful in aqueous and aqueous/organic solutions, but can easily be utilized in the solid and gaseous state. Moreover, since the reaction of maleimide with these sulfur compounds occurs in the presence of a wide pH range including acidic, neutral and basic solutions, the process of this invention does not require alkaline catalysts as has been known in the art for the reaction of olefins, other than maleimide, with hydrogen sulfide and mercaptans.